<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>

    <style>
        /* 两列左侧自适应布局 */

        .g-bd2 {
            margin: 0 0 10px;
        }

        .g-sd2 {
            position: relative;
            float: right;
            width: 230px;
            margin-left: -230px;
            background-color: #1ba1e2
        }

        .g-mn2 {
            float: left;
            width: 100%;
            background-color: palevioletred;
        }

        .g-mn2c {
            margin-right: 240px;
        }
    </style>

</head>

<body>

    <div class="g-bd2 f-cb">
        <div class="g-mn2">
            <div class="g-mn2c">
                <p>左侧自适应</p>
            </div>
        </div>
        <div class="g-sd2">
            <p>右侧定宽</p>
        </div>
    </div>


</body>

</html>